Interspinous process distraction system and method with positionable wing and method

ABSTRACT

An implant that is implanted between adjacent spinous processes for the relief of pain associated with the spine. The device has a spacer to distract apart the adjacent spinous processes. To minimize trauma to the patient, the device has a tapered tissue expander to distract a previously created opening between the adjacent spinous processes. The device also has two wings. The position of one wing is adjustable to allow for ease of assembly in a patent.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of, and claims priority to,U.S. patent application Ser. No. 10/014,118, filed Oct. 26, 2001, whichclaims benefit to U.S. Provisional Application No. 60/306,263, filedJul. 18, 2001, and is a continuation-in-part of U.S. patent applicationSer. No. 09/799,215, filed Mar. 5, 2001, which is a continuation-in-partof U.S. patent application Ser. No. 09/473,173, filed Dec. 28, 1999, nowU.S. Pat. No. 6,235,030, which is a continuation of U.S. patentapplication Ser. No. 09/179,570, filed Oct. 27, 1998, now U.S. Pat. No.6,048,342, which is a continuation-in-part of U.S. patent applicationSer. No. 09/474,037, filed Dec. 28, 1999, now U.S. Pat. No. 6,190,387,which is a continuation of U.S. patent application Ser. No. 09/175,645,filed Oct. 20, 1998, now U.S. Pat. No. 6,068,630, which is acontinuation-in-part of U.S. patent application Ser. No. 09/200,266,filed Nov. 25, 1998, now U.S. Pat. No. 6,183,471, which is acontinuation of U.S. patent application Ser. No. 09/139,333, filed Aug.25, 1998, now U.S. Pat. No. 5,876,404, which is a continuation of U.S.patent application Ser. No. 08/958,281, filed Oct. 27, 1997, now U.S.Pat. No. 5,860,977. All of the above applications and patents areincorporated herein by reference in their entireties.

FIELD OF THE INVENTION

[0002] The present invention is directed to an interspinous processimplant system and method which can, for example, distract apart andmaintain said distraction of adjacent spinous process.

BACKGROUND OF THE INVENTION

[0003] As the present society ages, it is anticipated that there will bean increase in adverse spinal conditions which are characteristic ofolder people. By way of example only, with aging comes increases inspinal stenosis (including, but not limited to, central canal andlateral stenosis), the thickening of the bones which make up the spinalcolumn and facet arthropathy. Spinal stenosis is characterized by areduction in the available space for the passage of blood vessels andnerves. Pain associated with such stenosis can be relieved by medicationand/or surgery. Of course, it is desirable to eliminate the need formajor surgery for all individuals and in particular for the elderly.

[0004] Accordingly, there needs to be developed procedures and implantsfor alleviating these and other spinal conditions, which procedures andimplants are minimally invasive, can be tolerated by the elderly and canbe performed preferably on an outpatient basis.

SUMMARY OF THE INVENTION

[0005] The present invention is directed to providing a minimallyinvasive apparatus and method for alleviating discomfort associated withthe spinal column.

[0006] The present invention provides for apparatus and method forrelieving pain by relieving the pressure and restrictions on theaforementioned blood vessels and nerves. Such alleviation of pressure isaccomplished in the present invention through the use of an implant andmethod which distract the spinous process of adjacent vertebra in orderto alleviate the problems caused by spinal stenosis and facetarthropathy and the like as well as other spinal ailments. While theimplant and method particularly address the needs of the elderly, theinvention can be used with individuals of all ages and sizes wheredistraction of the spinous process would be beneficial.

[0007] In one aspect of the invention, an implant is provided forrelieving pain comprising a device positioned between a first spinousprocess and a second spinous process. The device includes a spinalcolumn extension stop and a spinal column flexion non-inhibitor.

[0008] In a further aspect of the invention, the implant includes afirst unit having a body with a guide or tissue expander and a firstwing, with the first wing located at first end of the body. The guideextends from a second end of the body located distally from the firstwing. The implant further includes a sleeve or spacer provided over saidbody. The implant further includes a second wing and a device forsecuring the second wing to the first unit, wherein the sleeve or spaceris located between the first and second wings.

[0009] In yet still a further aspect of the invention, the implantincludes a sleeve which is rotatable relative to the wings of theimplant in order to be able to accommodate the anatomical structure ofspinous processes.

[0010] In still another aspect of the invention, the implant includes asecond wing that is movable toward the first wing after the second wingis assembled to the first unit in the patient. In this aspect a fastenercan be operated to cause the second wing to move toward the first wing.Accordingly, the implant can be easily assembled in the patient withoutconcern for the shape of the spinous processes and then the first andsecond wings can be drawn together so that these wings are positionedcloser to the spinous processes.

[0011] In another aspect the second wing includes an alignment tab whichis received in an alignment groove of the first unit in order to guidethe second wing as it is urged toward the first wing.

[0012] In another aspect of the invention a ramp mechanism is used tourge the second wing toward the first wing.

[0013] Other implants and methods within the spirit and scope of theinvention can be used to release pain associated with the spine and/orincrease the volume of the spinal canal thereby alleviating restrictionson vessels and nerves associated therewith and associated pain.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a perspective view of an embodiment of the presentinvention;

[0015]FIG. 2 is a top view of an embodiment of the adjustable wing ofthe present invention;

[0016]FIG. 3 is a perspective view of an embodiment of the fastener usedin the present invention;

[0017]FIG. 4 is cut-away view illustrating the interaction between thefastener and the adjustable wing with the adjustable wing is in a firstposition;

[0018]FIG. 5 is a cut-away view illustrating the fastener engaging theadjustable wing with the adjustable wing in a second position;

[0019]FIG. 6 is a side view illustrating an embodiment of the presentinvention as implanted between adjacent spinous processes; and

[0020]FIG. 7 is a front view of an embodiment of the present inventionas implanted between adjacent spinous processes.

DETAILED DESCRIPTION OF THE INVENTION

[0021] Referring to FIG. 1, the implant device 100 has a main body 101.The main body 101 includes a spacer 102, a first wing 104, a taperedfront end, lead-in guide or tissue expander 120 and an alignment track106. The main body 101 is inserted between adjacent spinous processes.Preferably, the main body 101 remains safely and permanently in placewithout attachment to the bone or ligaments. All of the components ofthe implant device 100 are made of biologically acceptable material suchas, but are not limited to, high strength titanium alloy or stainlesssteel. Preferably the first wing 104 is laser welded to the main body101.

[0022] The tip of the tissue expander 120 has the smallest diameter,allowing the tip to be inserted into a small initial dilated opening.The diameter and/or cross-sectional areas of the tissue expander 120then gradually increases until it is substantially similar to thediameter of the main body 101 and spacer 102. The tapered front end 120makes it easier for a physician to urge the implant device 100 betweenadjacent spinous processes. When urging the main body 101 betweenadjacent spinous processes, the front end 120 distracts the adjacentspinous processes to the diameter of the spacer 102. As shown in FIG. 1,the tissue expander 120 is a pyramid shape. In another embodiment thetissue expander preferably has an angle of twenty-five degrees thatallows it to clear the facet. This reduces the length of the front end120. One will appreciate that the shape of the tissue expander 120 canbe other shapes such as, but not limited to, cone shaped, or any othershape with a small lead-in cross-section expanding into a largercross-section. These types of shapes gradually distract the spinousprocesses to a sufficient distance so that the spacer 102 canconveniently fit between the spinous processes.

[0023] The spacer 102 can be made of stainless steel, titanium, asuper-elastic material or silicone or other biologically acceptablematerial. The material can be rigid or resilient as desired. As shown inFIG. 1, the spacer 102 is an elliptically shaped cylinder. One willappreciate that the spacer can consist of other shapes such as, but notlimited to, egg-shaped, round-shaped or saddle-shaped. For example, thespacer 102 can be saddle-shaped along the surface which engages thespinous processes so that the high edges and the lower central portionscan more fully accommodate the shape of the spinous processes.Preferably, the spacer 102 can swivel, allowing the spacer 102 toself-align relative to the uneven surface of the spinous process. Thisensures that compressive loads are distributed equally on the surface ofthe bone. By way of example only, the spacer 102 can have diameters ofsix millimeters, eight millimeters, ten millimeters, twelve millimetersand fourteen millimeters. These diameters refer to the height by whichthe spacer distracts and maintains apart the spinous process. Thus foran elliptical spacer the above selected height would represent the smalldiameter measurement from the center of the ellipse. The largestdiameter would be transverse to the alignment, of the spinous process,one above the other. Smaller and larger diameters are within the scopeof the invention.

[0024] The shape of the spacer 102 and for that matter the shape of theentire implant is such that for purposes of insertion between thespinous processes, the spinous processes do not need to be altered orcut away in any manner in order to accommodate the implant 100.Additionally, the associated ligaments do not need to be cut away andthere would be very little or no damage to the other adjacent orsurrounding tissues other than piercing through and separating, ordilating an opening in a ligament.

[0025] The first wing 104 has a lower portion 116 and an upper portion118. The upper portion 118 is designed to preferably accommodate, inthis particular embodiment, the anatomical form or contour of the L4(for an L4-L5 placement) or L5 (for an L5-S1 placement) vertebra. It isto be understood that the same shape or variations of this shape can beused to accommodate other vertebra. The lower portion 116 is alsorounded to accommodate, in a preferred embodiment, the vertebra. Thelower portion 116 and upper portion 118 of the first wing 104 will actas a stop mechanism when the implant device 100 is inserted betweenadjacent spinous processes. The implant device 100 cannot be insertedbeyond the surfaces of the first wing 104. Additionally, once theimplant device 100 is inserted, the first wing 104 can preventside-to-side, or posterior to anterior movement of the implant device100.

[0026] The implant device 100 also has an adjustable wing 110. Theadjustable wing 110 has a lower portion 108 and an upper portion 114.Similar to the first wing 104, the adjustable wing 110 is designed toaccommodate the anatomical form or contour of the vertebra.

[0027] The adjustable wing 110 is secured to the main body 101 with afastener 122 provided through tapered cavity 130. The adjustable wing110 also has an alignment tab 112. When the adjustable wing 110 isinitially placed on the main body 101, the alignment tab 112 engages thealignment track 106. The alignment tab 112 slides within the alignmenttrack 106 and helps to maintain the adjustable wing 110 substantiallyparallel with the first wing 104 in this preferred embodiment. When themain body 101 is inserted into the patient and the adjustable wing 110has been attached, the adjustable wing 110 also can preventside-to-side, or posterior to anterior movement.

[0028] Referring now to FIG. 2, the adjustable wing 110 includes theabove mentioned tapered cavity 130. The tapered cavity 130 has a middleportion 132, two end portions 134 and a tapered wall 131. The diameterof the middle portion 132 is larger than the diameter of either endportion 134. The tapered wall 131 has a larger diameter at the topsurface of the adjustable wing 110 than at the bottom surface.Accordingly a cone-like shape is formed. When the fastener 122 engagesthe main body 101 and is rotated, the fastener 122 travels into the mainbody 101 (see FIG. 1). As the fastener 122 travels into the main body101, the adjustable wing 110 will travel along the alignment track 106towards the first wing 104. The alignment tab 112 engages the alignmenttrack 106 and functions as a guide, keeping the adjustable wing 110 andthe first wing 104 substantially parallel to each other.

[0029] The fastener 122 has a tapered head 123, a middle section 136 andthreaded bottom section 138 (see FIG. 3). The top end of the taperedhead 123 was a diameter substantially similar to the diameter of the topsurface of the tapered cavity 130. The diameter of the tapered head 123is reduced as the tapered head meets the middle section 136. The slopeof the tapered head 123 is similar to the slope of the tapered cavity130 of the adjustable wing 110. The middle section 136 has a diametersubstantially similar to the end portions 134 of the adjustable wing110. The threaded bottom section 138 has a slightly larger diameter thanthe middle section 136 and is in one embodiment slightly smaller thanthe diameter of the middle portion 132 of the adjustable wing 110.

[0030] As the diameter of the end portions 134 are smaller than thediameter of the bottom section 138, the fastener 122 cannot initially beplaced through the end portions 134 of the adjustable wing 110.Accordingly, to fasten the adjustable wing 110 to the main body 101, thethreaded bottom section 138 of the fastener 122 is placed through themiddle portion 132 of the adjustable wing 110 and into the main body101. With a turn of the fastener 122, the threaded portion of the bottomsection 138 will engage the main body 101.

[0031] In another preferred embodiment the diameter of threaded bottomsection 138 is larger than the diameter of the middle portion of theadjustable wing 110. For this embodiment, the fasteners 122 is insertedinto the cavity 130 by slicing the cavity 130 (FIG. 2) through thethinnest portion of the wall, spreading the wall open, inserting themiddle section 136 in the cavity with the threaded bottom section 138projection below the cavity 130, and laser welding the wall closed. Theslicing step preferably includes using a carbide slicing device.

[0032] When the adjustable wing 110 is in the position furthest from theposition of the first wing 104, the tapered head 123 of the fastener 122is substantially out of, and not engaging, the tapered cavity 130 of theadjustable wing 110 (See FIG. 4). As the fastener 122 is rotated, thefastener 122 will continue to engage, and travel further into, the mainbody 101. As the fastener 122 travels downwardly into the main body 101,the tapered head 123 of the fastener 122 contacts the wall 131 of thetapered cavity 130. The adjustable wing 110 can freely slide back andforth, limited by the end portions 134 of the tapered cavity 130. Whenthe tapered head 123 contacts the wall 131 of the tapered cavity 130,the adjustable wing 110 moves towards the first wing 104 guided by thealignment tab 112 in the alignment track 106. Therefore, the adjustablewing 110 remains substantially parallel to the first wing 104 in thispreferred embodiment as the adjustable wing 110 moves toward the firstwing 104 (see FIG. 5). It is to be understood that the tab 112 and thetrack 106 can be eliminated in another embodiment of the invention.

[0033] As shown in FIG. 5, the tapered head of 123 of the fastener 122is mated in the tapered wall 131 of the adjustable wing 110.Accordingly, with this ramp mechanism, the adjustable wing 110 is urgedtoward the spinous processes and the first wing 104 and is locked inposition at its closest approach to the first wing 104. This arrangementallows the surgeon to loosely assemble the implant in the patient andthen urge the adjustable wing closer to the first wing, by rotatingfastener 122 into body 110 making the implanting method more tolerant tothe anatomy of the patient.

[0034] The structure of the spine is of course unique for every patient.Accordingly if the width of the spinous processes is excessive, theadjustable wing can be left in a position that is between that shown inFIG. 4 and that shown in FIG. 5. The separation between the first wing104 and the adjustable wing 110 can be incrementally adjusted by thenumber of turns of the fastener 122.

[0035]FIGS. 6 and 7 illustrate the position of the implant device 100 ina patient. As shown by FIG. 6, the lower portion 116 and upper portion118 of the first wing 104 function to prevent side-to-side movement,toward and away from the vertebral body ensuring that the implant device100 remains in place. Similarly, the adjustable wing 110 will alsoprevent excessive side-to-side movement. The wing also prevents motionin the direction of the main body into the space between the spinousprocesses.

[0036] The foregoing description of preferred embodiments of the presentinvention has been provided for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise forms disclosed. Obviously, many modificationsand variations will be apparent to the practitioner skilled in the art.The embodiments were chosen and described in order to best explain theprinciples of the invention and its practical application, therebyenabling others skilled in the art to understand the invention forvarious embodiments and with various modifications that are suited tothe particular use contemplated. It is intended that the scope of theinvention be defined by the following claims and their equivalence.

1. An implant for maintaining a space between adjacent anatomicalstructures, the implant comprising: a spacer; a wing; and ramp devicethat positions the wing relative to the spacer.
 2. An implant formaintaining a space between adjacent anatomical structures, the implantcomprising: a spacer; a wing; means for fastening the wing relative tothe spacer; and said fastening means including a ramp means for causingthe wing to move relative to the spacer.